Method for producing bituminous compositions

ABSTRACT

This invention relates to bituminous compositions and methods of producing the same. More particularly, the invention relates to the production of bituminous compositions formulated with performance-graded bitumen-containing solvent-free bitumen emulsions which exhibit controllable, temperature-dependent interfacial rheology. When employed in paving applications, these bituminous compositions develop adhesive strength and load-bearing strength properties at rates comparable to traditional hot mix paving compositions and at rates faster than traditional cold mix paving compositions.

This application is a continuation-in-part of and commonly assigned U.S.application Ser. No. 11/457,931, filed Jul. 17, 2006, now abandonedwhich is a continuation of PCT application No. PCT/US2005/002916, filedJan. 27, 2005, which claims priority from U.S. Provisional ApplicationSer. No. 60/545,713 filed Feb. 18, 2004.

BACKGROUND OF THE INVENTION

Cold mix paving compositions are made by mixing bitumen emulsion withaggregate at ambient temperature (i.e., temperature less than about 40°C.). However, certain problems have traditionally been associated withthe use of such compositions where no solvent is present. For example,when one employs a slow-setting bitumen emulsion in the construction ofload-bearing pavements the pavement is slow to cure and developsufficient strength values adequate to support heavy traffic and toresist moisture damage. However, the use of a quick-setting bitumenemulsion often leads to premature breaking of the emulsion duringhandling and compaction (resulting in the formation of high air voids).

Various methods have been employed in attempts to accelerate thestrength development of asphalt cold mixes made with bitumen emulsions.A number of these methods rely principally on shifting the pH of theemulsion or of the entire system to initiate or accelerate the break andcoalescence of emulsion. U.S. Pat. No. 4,008,096 to Knapp (which ishereby incorporated by reference) is exemplary of this approach,teaching the injection of pH-shifting agents to initiate the coalescenceof the emulsion.

However, these methods suffer from a lack of control of the timing ofthe pH-shifting chemistry. In any construction process involving bitumenemulsions, the premature breaking or coalescence of the bitumenemulsions adversely affects performance in production, handling,transport, and other end-use application operations. Prematurely brokenemulsions often fail to adequately coat aggregate and generally resultin high-viscosity bitumen-aggregate mixtures which can be troublesome todischarge from trucks, may excessively stick to paving equipment, andwhich can be difficult to compact to required pavement densities. Thus,the failure to effectively control the timing of the pH-shiftingchemistry commonly leads to premature rupture of the bitumen emulsionand a cascade of undesirable effects on mix processing and pavementapplications.

Attempts have been made to control the initiation of pH-shiftingchemistries in bitumen emulsions. For example, U.S. Pat. No. 5,256,195to Redelius (which is hereby incorporated by reference) teaches the useof anionic invert emulsions containing breaking agents in the aqueousphase of the water-in-oil emulsion in combination with slow-settingcationic emulsions as the main mixing and coating emulsion. Uponmechanical action of compaction the invert emulsion ruptures to exposethe alkaline aqueous phase to the cationic mixing emulsion, therebyshifting the pH of the system and initiating emulsion break. Thoseskilled in the art recognize that the use of mineral oils and othersolvents (i.e., so-called “cutter stocks”) can lead to improvements incompactability. However, the use of cutter stocks can also result indecreases in the early compressive strength of compacted pavement.Dosages of cutter stocks as little as 0.1% by weight of the emulsionoften decreases the compacted pavement compressive strength until suchtime as the cutter stock has evaporated into the atmosphere.

The formulation and production of fast-breaking bituminous emulsions bythe use of rapid-setting (or spray-grade) or quick-setting emulsifiersis generally known (e.g., U.S. Pat. No. 4,338,136 to Goullet, et al.,which is hereby incorporated by reference). However, approaches of thisnature suffer from two drawbacks which make them unsuitable forconstruction of load-bearing asphalt pavements that exhibit completeaggregate coating, compact to required densities in the field, anddevelop strength rapidly. First, at ambient temperatures rapid-settingemulsions do not adequately coat dense-graded aggregates commonly usedin construction of dense-graded, load-bearing pavements, because suchrapid-setting emulsions tend to break immediately upon contact withmineral aggregate surfaces. The term “rapid-setting” is a definingcharacteristic of such emulsions (i.e., they immediately rupture andliberate water upon contact with mineral aggregate). Second, at ambienttemperatures the immediate break of a rapid-setting emulsion produces amix with high viscosity. The failure to adequately compact leads to lowdensity pavements which fail under traffic due to deformation,disintegration, and/or, pot-hole formation (as water passes through thelow density layer into the base where supporting pavement layers aredegraded).

U.S. Pat. No. 5,743,950 discloses a process for preparing a bituminouscomposition by adding a hard bitumen binder having a penetration of lessthan 50 to a mixture of aggregates and a non-emulsified soft bitumenbinder component. A hard binder component is defined as a bindercomponent having a penetration of less than 200, as measured by ASTM D5at 25° C. A soft binder component is defined as a binder componenthaving a penetration of more than 700 as measured by ASTM D5 at 25° C.or a viscosity of less than 300 mPa·s. To obtain a bituminouscomposition with desired workability for load-bearing applications, anaggregate must be completely coated (i.e. mixed) with a soft binderprior to an addition of a hard binder. The bituminous composition mustinclude both a hard bitumen binder and a soft bitumen binder. First, anaggregate is mixed with the soft bitumen to ensure a complete surfacecoating with the soft bitumen. Then, a hard bitumen is added to amixture of aggregates and soft bitumen (i.e., aggregates surface coatedwith the soft bitumen) to impart stiffness and other desired propertiesfor load-bearing applications. The hard bitumen may be added either in aform of powder or emulsion to mixture of a soft binder and an aggregate,namely an aggregated must be pretreated with a soft binder prior to amixing with a hard binder. This process of producing bituminouscomposition requires a pretreatment of aggregate with soft binder priorto mixing with a hard binder; therefore, the equipment and process usedto produce the bituminous composition must be designed to allow apretreatment of aggregate.

Quick-setting emulsions are not suitable for the production ofload-bearing asphalt pavement compositions at ambient temperatures forsimilar reasons. The use of large volumes of water beyond that presentin the emulsion to promote coating of aggregate with quick-settingemulsions is not a feasible technique in the production of load-bearingpavements. First, load-bearing pavements are much thicker than thenon-load-bearing surfaces produced by slurry seal coatings andmicro-surfacings. The thicker load-bearing pavements must be compactedto density the mixture, as insufficient density can lead to rapidfailure of load-bearing pavements due to deformation, disintegration,and pot-hole formation. Large water volumes prevent compaction in thick,load-bearing pavements to required densities because water isincompressible. Moreover, quick-setting emulsions develop high viscositywhen stressed by high shear rate events such as compaction. As disclosedin U.S. Pat. Nos. 4,462,840 and 5,085,704, incorporated hereby byreference, retarders are generally needed to slow down the break ofquick-setting emulsion systems so that the materials might be handledand placed upon the intended construction surface prior to thedevelopment of such cohesive strength that they do not flow or cannot bespread.

Slow-setting emulsifiers are commonly employed in the production atambient-temperature of emulsion-based road paving compositions for loadbearing pavements. Slow-setting emulsifiers produce bituminous emulsionswhich require little or no water to completely coat the aggregatesurface. Moreover, the slow-setting nature of the emulsion yields a roadpaving composition with a controlled coalescence rate, so that the roadpaving mixture does not increase in viscosity to a point that it isunsuitable for handling, hauling, or compaction. With highly dense,high-fines aggregate gradations, slow-setting emulsions do not breakeither prior to or during compaction, thereby rendering the mixture easyto compact at ambient temperatures. However, pavement compositions madeat ambient-temperature with slow-setting bituminous emulsions are veryslow to develop adhesion and cure to strengths sufficient to bear thestress of heavy traffic.

In contrast to cold mix paving compositions, hot mix paving compositionsdo not contain bitumen emulsions, but are instead produced by mixingnon-emulsified bitumen with aggregate at elevated temperatures (usuallyin excess of 140° C.). The two most common hot mix facilities, drum mixplants and batch plants, heat aggregate in a rotating kiln to extremelyhigh temperatures to drive off all water adsorbed to the aggregate, aswell as all water absorbed within the surface pores of the aggregate.Quantitative removal of water is required (1) to ensure completeaggregate coating and (2) to ensure that the finished hot mixture ofaggregate and bitumen shows no moisture sensitivity in the finishedpavement layer once it is transported, laid down, and compacted.

Hot, dry aggregate produced in conventional hot mix operations is mixedwith bitumen (which is previously liquefied by heating to temperaturesfar in excess of its melting point) to produce what is known in theindustry as the “hot mix asphalt.” Hot mix asphalts generally must beproduced, laid down, and compacted at temperatures in excess of about160° C., as the compactability of the hot mix asphalt depends on thetemperature. If the mix cools, the asphalt viscosity increases and themixture cannot be compacted to the design density (known as percent airvoids). When a hot asphalt-aggregate mixture cools to temperatures belowabout 85° C., the handling, placement, and compaction of the mixturebecome extremely difficult and design densities (air voids) cannot berealized.

Therefore, it is an object of the present invention to disclose a methodof producing bituminous compositions that is simply and does not requirea pretreatment of aggregate prior to mixing with bitumen emulsion.

Another object of the present invention is to disclose bituminouscompositions which are suitable for use in paving applications and toprovide a paved road.

Yet another object of the present invention is to produce bituminouscompositions at temperatures substantially below those of hot mixasphalt compositions.

A further object of the present invention is to produce bituminouscompositions, using rapid-setting and/or quick-setting emulsifiers,which exhibit substantially complete aggregate coating, compact torequired densities in the field, and which rapidly develop load-bearingstrength.

Other objects, features and advantages of the present invention willbecome apparent from the following detailed description.

SUMMARY OF THE INVENTION

The objects of this invention are met by a method for producingbituminous compositions suitable for use in paving applications, made bycontrolling temperature-dependent interfacial rheology in a broad rangeof solvent-free, high-residue bitumen emulsions containing bitumen. Toproduce the solvent-free bitumen emulsions in these paving compositions,emulsifiers are employed with structural characteristics that impart lowinterfacial viscosity, low Marangoni effect, and high interfacialbitumen solubility, at elevated temperatures. The use of bitumens inthese emulsions with solubility parameters comparable with those of theemulsifier is preferred. The improved combination of emulsifiers, withstructural attributes that impart improved control of interfacialstability and rheology in solvent-free bitumen emulsions at elevatedtemperatures relative to ambient cold mix technologies and at reducedtemperatures relative to hot mix technologies, leads to load-bearingroad paving compositions with improved densification and acceleratedstrength development in the compacted state.

This invention teaches the formulation of solvent-free bitumenemulsions, which are based on bitumens and which exhibit controllable,temperature-dependent interfacial rheology, and use of said theseemulsions to fully coat aggregate, thereby producing bituminouscompositions suitable for the construction of load-bearing pavementsthat exhibit improved compaction to densities similar or superior tothose achieved in hot mix asphalt compositions and achieve cure rates totraffic-ready strengths far in excess of those achieved with compacted,conventional cold emulsion-based paving compositions and equal orsuperior to those of compacted, hot mix paving compositions.

When employed in paving applications, these bituminous compositionsdevelop adhesive strength and load-bearing strength properties at ratescomparable to traditional hot mix paving compositions and at ratesfaster than traditional cold mix paving compositions.

DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, reference may be made tothe accompanying drawings wherein FIGS. 1, 2, and 3 demonstrate theeffect of exposing bitumen emulsions to increasing shear stresses,thereby illustrating the high shear stability at elevated temperature(e.g., 60° C.-80° C.) exhibited by the bitumen emulsions of the presentinvention.

FIG. 1 shows the shear stress evaluation of a solvent-free bitumenemulsion produced in Example 1 containing 0.5% by total weight ofbitumen emulsion (bwe) of emulsifier (tallow polyalkylenepolyamines) at60% residue of PG70-22 bitumen;

FIG. 2 shows the shear stress evaluation of a bitumen emulsion producedin Example 8 containing 1.0% bwe of emulsifier (modified tall oil fattyacid condensate of polyethylene polyamine) at 60% residue of PG64-22bitumen; and

FIG. 3 shows the shear stress evaluation of a bitumen emulsion producedin Example 9 containing 0.75% bwe of emulsifier (a blend of modified andunmodified C16-C18 fatty acid condensate of polyethylene polyamine) at60% residue of PG70-22 bitumen.

DETAILED DESCRIPTION OF THE INVENTION

The present inventions now will be described more fully hereinafter withreference to the accompanying drawings, in which some, but not allembodiments of the invention are shown. Indeed, these inventions may beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will satisfy applicable legalrequirements.

The terms “bitumen” or “bituminous” in the present invention refer tonaturally-occurring bitumen and modified bitumen. They are also known as“asphalt.”

The bituminous compositions of the present invention comprise bitumenemulsion and aggregate, but in an absence of bitumen having apenetration number, as determined according to an ASTM standard methodD5 at 25° C., of more than 220 dmm. It is to be understood that the“aggregate” in the present invention also includes reclaimed asphaltpavement (RAP). The bitumen emulsion is solvent-free and containsbitumen, water, and an emulsifier or combination of emulsifiers havingstructural attributes that impart low interfacial viscosity, lowMarangoni effect, and high interfacial bitumen solubility at atemperature range of about 60° C. to about 120° C. to improveinterfacial stability and rheology of the emulsions.

Any known bitumen met specifications of performance grade, viscositygrade, or penetration graded may be used in the present invention.Suitable aggregates for use in the present invention have properties metspecifications established by the appropriate transportation authoritiesas suitable for use in construction of load-bearing pavements.

The bituminous compositions of the present disclosure do not require apretreatment of aggregation with soft bitumen prior to mixing withbitumen emulsion. The bituminous composition may be produced at atemperature from about 50° C. to about 140° C. by mixing the bitumenemulsion having a temperature from about 25° C. to about 95° C. withaggregate having a temperature from about 60° C. to about 140° C.

In one embodiment of the present invention, the disclosed bituminouscomposition comprises:

-   -   (a) solvent-free bitumen emulsion in an amount from about 2% to        about 10% by total weight of the bituminous composition, wherein        the emulsion comprises:        -   (i) bitumen in an amount from about 50% to about 75% by            total weight of the bitumen emulsion,        -   (ii) at least one active emulsifier in an amount from about            0.05% to about 2.0% by total weight of the bitumen emulsion,            and        -   (ii) water in an amount to complete the emulsion; and    -   (b) aggregate in an amount from about 90% to about 98% by total        weight of the bituminous composition; and    -   wherein the bituminous composition is in an absence of bitumen        having a penetration number of more than 220 dmm as determined        according to an ASTM standard method D5 at 25° C.

In one embodiment of the present invention, the disclosed bituminouscomposition comprises:

-   -   (a) solvent-free bitumen emulsion in an amount from about 2% to        about 10% by total weight of the bituminous composition, wherein        the emulsion comprises:        -   (i) bitumen in an amount from about 60% to about 70% by            total weight of the bitumen emulsion,        -   (ii) at least one active emulsifier in an amount from about            0.05% to about 2.0% by total weight of the bitumen emulsion,            and        -   (iii) water in an amount to complete the emulsion; and    -   (b) aggregate in an amount from about 90% to about 98% by total        weight of the bituminous composition; and    -   wherein the bituminous composition is in an absence of bitumen        having a penetration number of more than 220 dmm as determined        according to an ASTM standard method D5 at 25° C.

In one embodiment of the present invention, the disclosed bituminouscomposition comprises:

-   -   (a) solvent-free bitumen emulsion in an amount from about 2% to        about 10% by total weight of the bituminous composition, wherein        the emulsion comprises:        -   (i) bitumen in an amount from about 50% to about 75% by            total weight of the bitumen emulsion,        -   (ii) at least one active emulsifier in an amount from about            0.08% to about 0.75% by total weight of the bitumen            emulsion, and        -   (iii) water in an amount to complete the emulsion; and    -   (b) aggregate in an amount from about 90% to about 98% by total        weight of the bituminous composition; and    -   wherein the bituminous composition is in an absence of bitumen        having a penetration number of more than 220 dmm as determined        according to an ASTM standard method D5 at 25° C.

In one embodiment of the present invention, essentially all of thebitumen in the emulsion has a penetration number of less than 220 dmm asdetermined according to an ASTM standard method D5 at 25° C.

In addition to bitumens, modified bitumens may be used in the presentdisclosure. As used herein, the “bitumens” and “modified bitumens” arethose which exhibit rheological properties that are appropriate forpaving applications under specific climatic conditions, for example,those which conform to the Strategic Highway Research Program (SHRP)pavement binder specifications. The bitumen component may be naturallyoccurring bitumens (such as Trinidad Lake asphalt and the like), orderived from crude oil. Also petroleum pitches (such as asphalt)obtained by a cracking process and coal tar can be used as well asblends of bituminous materials.

Any additive which is traditionally added to bitumen to produce amodified bitumen meeting property specifications and performancestandards (such as SHRP) are suitable. Such additives include, but arenot limited to, natural rubbers, synthetic rubbers, plastomers,thermoplastic resins, thermosetting resins, elastomers, and combinationsthereof. Examples of these additives include styrene-butadiene-styrene(SBS), styrene-butadiene-rubber (SBR), polyisoprene, polybutylenes,butadiene-styrene rubbers, vinyl polymers, ethylene vinyl acetate,ethylene vinyl acetate derivatives, neoprene and the like. It ispreferred that the modified bitumen contain at least one member selectedfrom the group consisting of styrene-butadiene-styrene,styrene-butadiene-rubber, sulfur-modified bitumen, acid-modified bitumenand combinations thereof. It is well within the ability of a skilledartisan to produce modified bitumen containing the noted additives.

Where desired, additional additives traditionally employed in theproduction of bitumen emulsions may be incorporated into the aqueousphase of the bitumen emulsion in order to adjust the characteristics ofthe finished mix. Suitable additives include styrene-butadiene-rubberlatex, polyisoprene latex, neoprene, associative thickeners, starches,salts, and the like.

From about 0.05% to about 2.0% (preferably from about 0.1% to about0.75%, and more preferably from about 0.08% to about 0.5%) by totalweight of the bitumen emulsion of the present disclosure is comprised ofat least one emulsifier. Suitable emulsifiers include: amphotericemulsifiers, cationic emulsifiers, nonionic emulsifiers and combinationsthereof.

Bitumen emulsions are of the oil-in-water type; they consist of asuspension of bituminous particles dispersed in the water phase. Theseparticles have, in the case of cationic emulsions, a positive charge.The pH of cationic emulsions is below pH 7.0. As the term implies,amphoteric emulsifiers are characterized by the capacity to lowerinterfacial tensions between dissimilar materials (e.g., bitumen andwater) at pH values both above and below 7.0. The charge of thedisperse-phase oil droplets in amphoteric emulsions may be eitherpositive or negative. It is well within the ability of those skilled inthe art to combine the bitumen and the emulsifiers taught herein toprepare the solvent-free bitumen emulsions of the present disclosure.

Ionic emulsifiers which are suitable for use in the present disclosureinclude amphoteric emulsifiers, cationic emulsifiers, and combinationsthereof.

As used herein the term “amphoteric emulsifiers” includes bothmono-amphoteric and polyamphoteric emulsifiers. Amphoteric emulsifierswhich are suitable for use in the present disclosure include, but arenot limited to, the following: lithium C-12 to C-24 alkyl amidopropylhalide methyl carboxylate betaines, sodium C-12 to C-24 alkylamidopropyl halide methyl carboxylate betaines, potassium C-12 to C-24alkyl amidopropyl halide methyl carboxylate betaines, lithium C-12 toC-24 alkyl amidopropyl halide phosphate betaines, sodium C-12 to C-24alkyl amidopropyl halide phosphate betaines, potassium C-12 to C-24alkyl amidopropyl halide phosphate betaines, lithium C-12 to C-24 alkylamidopropyl halide sulphate betaines, sodium C-12 to C-24 alkylamidopropyl halide sulphate betaines, potassium C-12 to C-24 alkylamidopropyl halide sulphate betaines, C-12 to C-24 fatty ester acrylicderivative of polyethylene polyamines such as those obtained by reactingC-12 to C-24 fatty acids with acrylic acid, maleic anhydride, fumaricacid, and/or other ene- and dieneophiles, and then reacting theresulting chemical with polyethylene polyamines, rosin ester acrylatederivative of polyethylene polyamines such as those obtained by reactingrosin acids with acrylic acid, maleic anhydride, fumaric acid, and/orother ene- and dieneophiles, and then reacting the resulting chemicalwith polyethylene polyamines.

Cationic emulsifiers which are suitable for use in the presentdisclosure include, but are not limited to, the following: fattyimidazolines derived from C-12 to C-24 fatty acids; fatty imidoaminesderived from C-12 to C-24 (preferably C-16 to C-18) fatty acids; rosinimidoamines such as those obtained by reacting rosin acids with maleicanhydride, fumaric acid, and/or other ene- and dieneophiles and thenreacting the resulting chemical with polyalkylenepolyamines; fattyamidoamines derived from C-12 to C-24 (preferably C-16 to C-18) fattyacids, rosin amidoamines such as those obtained by reacting rosin acidswith maleic anhydride, fumaric acid, and/or other ene- and dieneophilesand then reacting the resulting chemical with polyalkylenepolyamines;saturated C-12 to C-24 alkyl monoamines, unsaturated C-12 to C-24 alkylmonoamines, saturated C-12 to C-24 alkyl polypropylenepolyamines;unsaturated C-12 to C-24 alkyl polypropylenepolyamines; C-12 to C-24alkyl monoamine polyoxyethylene such as those obtained by reacting C-12to C-24 alkyl monoamines with ethylene oxide; C-12 to C-24 alkylmonoamine polyoxypropylene such as those obtained by reacting C-12 toC-24 alkyl monoamines with propylene; C-12 to C-24 alkyl polypropylenemonoamines polyoxyethylene such as those obtained by reacting C-12 toC-24 alkyl polypropylenepolyamines with ethylene oxide; C-12 to C-24alkyl polypropylene monoamines polyoxypropylene such as those obtainedby reacting C-12 to C-24 alkyl polypropylene monoamines with propyleneoxide; saturated C-12 to C-24 alkyl aryl monoamines, unsaturated C-12 toC-24 alkyl aryl monoamines; saturated C-12 to C-24 alkyl arylpolypropylenepolyamines, unsaturated C-12 to C-24 alkyl arylpolypropylenepolyamines; C-12 to C-24 quaternary amines; C-12 to C-24alkyl ether amines; C-12 to C-24 alkylether polyamines; C-12 to C-24alkyl polypropylene polyamine N-oxides; amine derivatives of tannins,amine derivatives of phenolic resins; amine derivatives of lignins,amine-modified polyacrylates; and combinations thereof. It is preferredthat the cationic emulsifier be a member selected from the groupconsisting of saturated C-12 to C-24 alkyl monoamines, unsaturated C-12to C-24 alkyl monoamines, saturated C-12 to C-24 alkylpolypropylenepolyamines, unsaturated C-12 to C-24 alkylpolypropylenepolyamines, and combinations thereof. It is furtherpreferred that the cationic emulsifier be a blend of at least one memberselected from the group consisting of saturated and unsaturated C-12 toC-24 alkyl monoamines with at least one member selected from the groupconsisting of saturated and unsaturated C-12 to C-24 alkylpolypropylenepolyamines. As used herein, the term “cationic emulsifiers”includes the above-noted compounds and their derivatives.

The emulsifiers of the present disclosure not only convey thehigh-temperature shear-stability needed for mixing (and subsequentcompacting) of the bituminous compositions, but also impart a highviscosity to the bitumen emulsion (so that no thickener is needed foremulsion stability or for increased film coating on the aggregate) toenhance bitumen wetting of the aggregate surface, and to lowerinterfacial tension between the bitumen film and aggregate (so that astrong adhesive bond is maintained and water damage to the pavement isprevented).

Emulsifier formulations are further classified as rapid-setting (i.e.,spray-grade), quick-setting, and slow-setting depending on the speedwith which a given emulsion, using an economical dosage of emulsifier,will break upon contact with mineral aggregate. While rapid-setting,quick-setting, and slow-setting emulsifiers are suitable for use in thepresent disclosure, it is preferred to employ rapid-setting orquick-setting emulsifiers. It is further preferred to employrapid-setting emulsifiers with dense-graded aggregate. This preferencearises from the need to control such emulsion properties as theinterfacial viscosity, Marangoni effect, and interfacial bitumensolubility at the elevated temperature of the present disclosure (i.e.,about 50° C. to about 120° C.) and concurrently at low emulsifierdosages. Quick-setting and slow-setting emulsifiers require higherdosages and do not impart the target interfacial properties in thefinished emulsion. Additionally, high emulsifier dosages are costly,contribute to low rates of compressive strength development, andincrease moisture sensitivity in the finished pavement.

It is preferred that the bitumen emulsion be solvent-free. Environmentalconcerns have driven the reduction, up to elimination, of organicsolvents from paving bitumen emulsions. However, for technical reasonstotal elimination has not been available in all paving applicationsprior to the availability of the present disclosure. Thus, in certaindistricts the term “solvent-free” is defined to include a minor portionof organic solvents. For example, “solvent-free” has at one time beendefined in the state of Pennsylvania to include up to 4% organicsolvents. For the purposes of this disclosure, therefore, where desiredthe bitumen emulsion may contain at least one solvent (such as naphtha,kerosene, diesel, flux, and the like) at a level less than that neededto facilitate either: 1) the mixing of the bituminous composition atambient temperature to yield fully-coated aggregate, or 2) thecompaction of the bituminous composition at ambient temperatures. Whereadded, it is preferred in the present disclosure that the level ofsolvent be less than about 1.0% by total weight of the bitumen emulsion.As used herein, the term “ambient temperatures” means an environmentaltemperature of less than about 40° C.

Where desired, the bitumen emulsions of the present disclosure may bestored at temperatures in the range of about 60° C. to about 80° C. forprolonged periods of time without adversely affecting the particle sizedistribution of the emulsions.

The bituminous compositions of the present disclosure are produced at atemperature in the range of about 50° C. to about 140° C. (preferably inthe range of about 55° C. to about 120° C., and more preferably in therange of about 60° C. to about 80° C.) by mixing from about 2.0% toabout 10% by total weight of the bituminous composition of the bitumenemulsion at a temperature in the range of about 25° C. to about 95° C.(preferably in the range of about 60° C. to about 80° C.), and fromabout 90% to about 98% by total weight of the bituminous composition ofaggregate at a temperature in the range of about 60° C. to about 140° C.(preferably in the range of about 60° C. to about 120° C.). It will beunderstood by those skilled in the art that the bitumen emulsion may bemixed cold (e.g., at ambient temperatures) and then heated.

Aggregate used in paving materials and road construction, roadrehabilitation, road repair, and road maintenance are derived fromnatural and synthetic sources. As in any construction process, aggregateare selected for asphalt paving applications based on a number ofcriteria, including physical properties, compatibility with the bitumento be used in the construction process, availability, and ability toprovide a finished pavement that meets the performance specifications ofthe pavement layer for the traffic projected over the design life of theproject. Among the aggregate properties that is key to successful roadconstruction is gradation, which refers to the percent of aggregateparticles of a given size. For most load-bearing asphalt pavements,three gradations are common: dense-graded, gap-graded, and open-graded.Dense-graded aggregate exhibit the greatest mineral surface area (perunit of aggregate). Open-graded aggregate largely consist of a single,large-sized (e.g., around 0.375 to 1.0 inch) stone with very low levels(typically less than about two percent of the total aggregate) of fines(material less than 0.25 inch) or filler (mineral material less than0.075 mm). Gap graded aggregate fall between dense-graded andopen-graded classes. Reclaimed asphalt pavement (RAP) material generallyreflects the gradation of the pavement from which the reclaimed materialwas obtained. If the original pavement was a dense-graded mix, the RAPwill also be dense graded, although the filler content is generallyobserved to be lower than the design limits of the origin aggregatespecifications.

Any aggregate which is traditionally employed in the production ofbituminous paving compositions is suitable for use in the presentdisclosure, including dense-graded aggregate, gap-graded aggregate,open-graded aggregate, reclaimed asphalt pavement, and mixtures thereof.Aggregate which is not fully dried can be employed in the presentdisclosure.

Where used in paving applications, it is preferred that the bituminouscompositions of the present disclosure be applied to the surface to bepaved at a temperature in the range of about 50° C. to about 120° C.(preferably in the range of about 55° C. to about 100° C., and morepreferably in the range of about 60° C. to about 80° C.).

Once applied to the surface to be paved, the bituminous compositions ofthe present disclosure can be compacted as desired using any of thecompaction methods traditionally employed for paving applications. It ispreferred that the applied bituminous compositions be compacted to anair void content comparable to hot mix pavement compositions made attemperatures exceeding 140° C. having substantially equivalent aggregategradation and bitumen content.

Likewise, it is further preferred that the applied bituminouscompositions be compacted to an air void content lower than comparablecold mix pavement compositions made at ambient temperatures (i.e.,temperatures less than about 40° C.) having substantially equivalentaggregate gradation and bitumen content.

It is also further preferred that the applied bituminous compositions becompacted to develop load-bearing strength at a rate comparable to hotmix pavement compositions made at temperatures exceeding 140° C. havingsubstantially equivalent aggregate gradation and bitumen content.

Likewise, it is also further preferred that the applied bituminouscompositions be compacted to develop load-bearing strength at a fasterrate than that developed by comparable cold mix pavement compositionsmade at ambient temperatures having substantially equivalent aggregategradation and bitumen content.

Strength development in cold mix pavement compositions is a function ofthe development of adhesion between bitumen and aggregate. It is,therefore, preferred that the applied bituminous compositions becompacted to develop adhesion between bitumen and aggregate at a fasterrate than that developed by comparable cold mix pavement compositionsmade at ambient temperatures having substantially equivalent aggregategradation and bitumen content.

The method of the present disclosure is suitable for use in thin liftoverlay paving applications. Thin lift overlays is a maintenance pavingtechnique that traditionally involves the placement of a thin lift of abituminous composition produced according to standard hot-mix proceduresat temperatures normally exceeding 165° C. and applied at correspondingtemperatures in the field to an existing, damaged or distressed pavementsurface. The current thin lift technology using hot-mix bituminouscompositions commonly suffers from two chief deficiencies. The hotbituminous compositions tend to cool quickly, making it difficult toextend (i.e., spread) onto the existing pavement surface (at ambienttemperatures) that is in need of maintenance or repair. This rapidcooling of the thin lift of hot bituminous material can cause compactiondifficulties. The problems that arise in construction (e.g., extension,spreading, and compaction) due to rapid cooling can be aggravated by theuse of polymer-modified bitumens. Polymer-modified bitumens haveviscosities higher than unmodified bitumens at a given temperature.Thus, hot-mix bituminous compositions (mixtures with aggregate) madewith polymer-modified bitumens are more viscous than equivalentbituminous compositions made with unmodified bitumen at a givenconstruction temperature. As a consequence of this increased viscosityand increased resistance to flow, a thin lift bituminous compositionmade with polymer-modified bitumen can exhibit even greater problems inhandling and construction as the material cools rapidly.

Where desired, the methods and bituminous compositions of the presentdisclosure can be employed in the production of bituminous pavingblocks. In this technology, bitumen emulsion and aggregate are mixed toform a bituminous composition that is cast in molds, compacted, andallowed to cure. The cured blocks (or bricks) are used to constructpavements.

Where used in the production of bituminous paving blocks, it ispreferred that the bituminous compositions of the present disclosure becast in the mold and compacted at a temperature in the range of about50° C. to about 120° C. (preferably in the range of about 55° C. toabout 100° C., and more preferably in the range of about 60° C. to about80° C.).

Due to the enhanced compaction (leading to higher density and higherstrength) and accelerated cure rates (leading to increased productionrates and improved manufacturing economics) exhibited by the bituminouscompositions of the present disclosure, the employment of the methodsand bituminous compositions of the present disclosure offersimprovements over the construction of these blocks using traditionalcold mix paving compositions.

Bituminous compositions of the present disclosure should be maintainedat a temperature in the range of about 50° C. to about 120° C.(preferably in the range of about 55° C. to about 100° C., and morepreferably in the range of about 60° C. to about 80° C.) for the periodof time between the production of the bituminous compositions and theiruse in paving applications. It is preferred that the bituminouscompositions be maintained at these temperatures in closed systems (suchas relatively large stockpiles, storage silos, covered transportvehicles, and the like) to prevent evaporation of moisture.

Equipment traditionally utilized in the production of asphalt emulsionmixes includes pug mills of either batch or continuous variety. Pugmills impart high shear to the emulsion as it is ground with coarseaggregate, fines, and filler. Hot mix asphalt compositions are typicallyproduced in continuous or batch operations. Continuous plants typicallyuse drum mixtures of either parallel flow or counter flow variety. Thesemixers are high shear mixers as aggregate (which is heated in the drumor batch mixer to the specified process temperatures) tumbles down theinclined drum and as bitumen emulsion is sprayed onto the warmaggregate. The emulsion treated aggregate also tumbles downward throughthe drum mixer. The interior wall of most drum mixers is lined withvanes that repeatedly catch the mix, lift it up as the drum rotates, anddeposit it back to the bottom of the drum. Drum and batch plants arecapable of throughput of many hundred tons of paving material per hour.While it is preferred to employ drum mixers or batch mixers in theproduction of the bituminous compositions of the present disclosure, anymethod of mixing bitumen emulsion and aggregate traditionally utilizedin the production of paving compositions can be used.

A common problem associated with the high shear event of mixing has beena coarsening of the emulsion. The emulsifier formulations describedherein impart high-temperature rheological properties to thesolvent-free emulsion, which in turn stabilize the emulsion against themechanical stresses imparted on the emulsion by the mechanical action ofmixing with aggregate at elevated temperatures. These mechanical andshear stresses have commonly caused a coarsening of the emulsion withmost traditional emulsifier formulations, leading to a reduction in thedegree of aggregate coating and an increase in the viscosity of the mix,with the latter resulting in poor densification of the pavingcomposition during compaction. Poor densification during compaction canresult in a number of pavement distress problems (such as rutting,pot-hole formation, and raveling). While the use of high emulsifierdosages can mitigate this coarsening, such dosages can also retard thedevelopment of compressive strength, an undesirable outcome.

The rheology of the disperse-phase droplets in the bitumen emulsions ofthe present disclosure directly influences the behavior of the emulsionswhen mixed at elevated temperatures with heated aggregate. The rheologyat the oil-water interface is, in turn, controlled by the structure andchemistry of the emulsifiers. Emulsifier structure and chemistry affectthe energy required to disperse the emulsifier at the interface.Emulsifier structure and chemistry determine the shear stability of theoil-water droplets against coalescence under high-temperature shearconditions, such as those exhibited during mixing of emulsions andaggregate at temperatures above ambient. Emulsifier structure andpacking affect the interfacial fluidity or viscosity. Further, properchoice of emulsifier structure affects the magnitude of the effect onthe interfacial viscosity.

The observation that some chemical entities produce the desired effectof rapid early strength development, while others do not, furthersuggests that the chemistry of the formulation is also an influencingfactor. A further observation that the bitumen emulsions which behave asdesired have higher levels of shear stability than those which do notshow this behavior would suggest this chemical contribution results fromthe emulsifier. The observation that strength development in thebituminous compositions of the present disclosure is associated withbetter compressibility than traditional cold mixes very stronglysuggests that the specific physico-chemical effect is a change in therheology of the bitumen droplets within the emulsion. The early strengthdevelopment exhibited by the bituminous compositions of the presentdisclosure which is more characteristic of a hot mix than a cold mixalso indicates that the rheological response of the bitumen droplets isan interfacial rather than a bulk response.

A variant of the above mechanism which is consistent with the currentlyavailable data and observations of the present disclosure consists of aheat dependant activation of the interfacial solubility of the ionicemulsifier. Interfacial solubility within the present context may bedefined as localization of the emulsifier at the interface. Nodistinction should be made at the present time between surfaceadsorption (the emulsifier resides not within the aqueous phase of thebitumen emulsion but at the interface with certain functional groupspenetrating into the bitumen), penetration of the interface by theemulsifier (residing within the surface of the bitumen droplet withfunctional groups oriented towards the water and others oriented towardsthe interior of the bitumen phase of the bitumen emulsion), or completeresidence within the bitumen phase of the bitumen emulsion but at theinterface (the mirror image of surface adsorption).

The interactions of the emulsifier with the interfacial region of adispersed bitumen droplet can influence the interfacial rheology of thebitumen in two ways. The emulsifier can provide a lubricity layer orslip plane between and amongst the droplets or they can disrupt thestructure of the asphaltene fractions of the bitumen at and within theinterface. It must be noted that the hardness and flow resistance ofbitumen is to a large degree a function of the asphaltene componentswithin a particular bitumen. The model of bitumen favored by thoseworking in the area of heavy oil processing consists of asphaltenes ofvarying molecular weights existing as dissolved and colloidal entitieswithin the maltene phase of the bitumen. Penetration of the associatedasphaltenes within a bitumen by molecules or parts of molecules willtend to disrupt the surface structure of the bitumen. The concomitantresult of this is a reduction in the resistance to flow of the surfaceregions of the droplets. By definition, the resistance to flow isreferred to as viscosity. In order to penetrate the structure formed bythe asphaltenes, a foreign molecule or parts of that molecule must havesimilar cohesive energy density to the asphaltenes. From a thermodynamicpoint of view, this means that if the molecules of two differentsubstances have similar cohesive densities and are placed in closeproximity to each other and subjected to the same conditions (such astemperature, pH, ionic strength etc.) the molecules of the two willintermingle at the level of individual molecules. This is by definitionsolvation or dissolution. By convention, the substance present ingreater concentration is referred to as the solvent and the other, thesolute.

One of the most widely accepted means of quantitatively describing thecohesive energy density is by use of a parameter called the solubilityparameter. This number is actually the square root of the cohesiveenergy density. Various models of the solubility parameter have beenproposed. The most widely referred to models are those of Hildebrand andHansen. As a solubility class, asphaltenes have a solubility parameter(δ) of 19-24 (MPa)^(1/2). Consequently, a substance with a solubilityparameter within or slightly above this range should in principledissolve in and disrupt the internal structure of the asphaltenes of anasphalt. Somewhat relevant to this argument are references to the factthat London dispersion forces are the major contributors to the strengthand complexity of the asphaltene structure within a given asphalt. Thismust be considered when using the more complex Hansen solubilityparameter instead of the Hildebrand version. Further to this, it iscommon practice to quantify the asphaltene fraction of bitumen byprecipitating the asphaltenes from a sample of that asphaltene via theaddition of either pentane or heptane. These two hydrocarbons haveHildebrand solubility parameters of 14.3 and 15.1 (MPa)^(1/2),respectively. Consequently, solubility parameters in the range of 19-25(MPa)^(1/2) or higher will identify molecules or parts of moleculeswhich have the ability to disrupt asphaltene structure and consequentlyfluidize that bitumen, while molecules or parts of molecules withsolubility parameters similar to those of the C5-C7 hydrocarbons havethe potential to reflocculate or coagulate already dispersedasphaltenes.

From a molecular point of view, the cohesive energy density orsolubility parameter of a molecular is determined by its chemicalcomposition or make-up. Consequently, it is also a function of the rawmaterials and the manufacturing process used to manufacture thatsubstance, or more succinctly, the nature of the specific substance. Inthe case of emulsifiers, the solubility parameter can also be related tothe hydrophile-lipophile balance (HLB) by the expression:

${HLB} = \frac{\left( {\delta - 16.8} \right) \times (54)}{\delta - 12.3}$

In the present work, a series of emulsifiers was shown to demonstratethe compressibility and early strength development seen to be anadvantage of the method of the present disclosure. Those emulsifierswere observed to have functional groups with solubility parameters inthe range of 24-25 (MPa)^(1/2) and hydrophobes in the range of 8-16(MPa)^(1/2). The most dramatic failure was observed with an emulsifiersystem with a low level of functionality of the requisite type andsolubility parameter. The solubility parameter of the entire emulsifiersystem was also well into the high 30's to low 40's. Additionally, theusable functionality which was present was shown by model studies to besterically hindered from penetration into the interfacial regions of thebitumen/water interface. It is thus a preferred embodiment of thepresent disclosure to formulate the bitumen emulsions with emulsifierscomprised of functional groups and structure, which impart the requisitesolubility characteristics (as described above) for controllingtemperature-dependent interfacial rheology.

The following examples are provided to further illustrate the presentdisclosure and are not to be construed as limiting the disclosure in anymanner.

In the following examples, the bituminous compositions of bitumenemulsion and aggregate were either mixed with an automated bucket mixer(Example 1) or by hand (Examples 2-14). The mixtures of bitumen emulsionand aggregate were compacted immediately after preparation while themixtures were at production temperatures. A Strategic Highway ResearchProgram (SHRP) gyratory compactor (commercially available from PineInstruments) was used to compact the bituminous compositions into pillsat a gyratory angle of 1.25° and a ram pressure of 600 kPa using 30gyrations. Immediately after compaction, the bituminous compositionpills were placed in a 25° C. oven for curing. After curing, the pillswere evaluated for compressive strength (i.e., Marshall stability). Thecompressive strength value obtained after four hours of curing atambient temperature (25° C.) is referred to herein as “early strength.”A stabilometer (commercially available from Pine Instruments) was usedto measure the compressive strength of the compacted specimens. The meanparticle sizes of each of the bitumen emulsions employed in thefollowing examples were less than 10 microns.

The aggregate used in the following examples was crushed graniteconforming to gradation and property specifications for a dense-graded,½-inch nominal paving mixture commonly used for production of pavementwearing courses. All aggregate samples were oven-dried (110° C.) beforeusage to remove moisture. In the comparative cold mix examples, theaggregate was allowed to cool to room temperature before mixing with thebituminous emulsion. In the comparative hot mix examples, the aggregatewas heated to a temperature in the range of about 140° C. to 160° C.before mixing with bitumen heated to an equivalent temperature. Allgraded aggregate samples were 1,000 grams.

Coating was measured using a modification of the commonly knowninstrumental luminescence method of Deneuvillers et al. Coating valuesin the examples below are expressed in percentages, indicating themeasured percentage of aggregate surface coated by bitumen.

EXAMPLE 1

Bituminous compositions of the present disclosure were prepared by thefollowing procedure. Solvent-free bitumen emulsions were prepared usingone of three different emulsifiers (A, B, and C) based on alkylpolyamines at dosages ranging from 0.3% to 0.5% by total weight of therespective bitumen emulsion. Emulsifier A was a blend of 0.4% by totalweight of the bitumen emulsion (bwe) of saturated and unsaturatedC16-C18 tallow tripropylenetetramines and 0.1% bwe of saturated andunsaturated C16-C18 tallow monoamines. Emulsifier B was 0.3% bwe ofsaturated and unsaturated C16-C18 tallow polypropylenepolyamine blends.Emulsifier C was a blend of 0.45% bwe of alkyl polypropylenetetramineand 0.01%-0.05% bwe of a mixture of saturated and unsaturated C16-C18alkyl monoamines, -diamines, and -triamines. The respective emulsifierswere dissolved in warm water and treated with hydrochloric acid solutionto lower the pH to 2.0. The aqueous solution of emulsifier(s) in water(called the “soap solution”) was heated to 55° C. and added to an Atomixcolloid mill.

The bitumen employed in this example was of Venezuelan origin and had aperformance-grade of PG64-22. The bitumen was heated to 130° C. andadded to the Atomix colloid mill, wherein the soap solution and bitumenmixture was processed to produce bitumen emulsion. The bitumen contentof the finished bitumen emulsions were about 60-63% bwe. The bitumenemulsions were subsequently diluted with water to 53.3% bitumen contentprior to mixing with aggregate.

As noted above, the aggregate used was crushed granite conforming togradation and property specifications for ½-inch nominal wearing coursepaving aggregate. The aggregate as received from the quarry was ovendried to remove moisture. The dried aggregate was separated into sizefractions from particles passing the 12.5-mm sieve to particles passingthe 0.075 micron sieve. The fractions were combined in quantities togive an aggregate gradation conforming to the standard for ½-inchnominal, dense-graded aggregate for surface and wearing coursepavements. This combination of aggregate water-free fractions meetingthe ½-nominal gradation standard is referred to as the graded aggregate.

For bituminous compositions made in this example according to the methodof the present disclosure, the graded aggregate was heated to about 80°C. in an oven while the bitumen emulsion was heated to about 60° C.About 1,000 grams of heated graded aggregate were placed in a 1-gallonstainless steel bucket, and the bucket was placed in the automaticbucket mixer. To the 1,000 grams of aggregate at 80° C. was added, withstirring, 90 g of 60° C. bitumen emulsion. The mixing was continued foran additional 60 seconds to produce bituminous compositions containingabout 4.8% bitumen by total weight of the graded aggregate.

The resulting bitumen compositions (having a temperature in the range ofabout 60° C. to about 80° C.) were added immediately to a 100-mmdiameter gyratory compaction mold, which had been preheated to 60°C.-80° C. The bitumen compositions were then compacted using 30gyrations of a SHRP Pine gyratory compactor at 600 kPa pressure and agyration angle of 1.25°.

The compacted bituminous compositions were placed in a 25° C. oven andallowed to cure for four hours. After four hours of curing, the physicaland performance properties of the compacted and cured bituminouscompositions were measured.

For comparison purposes, a series of cold mix bituminous compositionswere produced having equivalent aggregate gradation and bitumen content.The procedure for the production of the bituminous composition of thepresent disclosure noted above was followed for producing these cold mixbituminous compositions with the exception that the bitumen emulsion andthe graded aggregate were each at ambient room temperature (23° C.) whenmixed in the bucket mixer.

The resulting cold mix bitumen compositions at ambient temperature wereadded immediately to a 100-mm diameter gyratory compaction mold, whichwas also at ambient temperature. The ambient-temperature bitumencompositions were then compacted using 30 gyrations of a SHRP Pinegyratory compactor at 600 kPa pressure and a gyration angle of 1.25°.

The compacted bitumen compositions were placed in a 25° C. oven andallowed to cure for four hours. After four hours of curing, the physicaland performance properties of the compacted and cured cold mixbituminous compositions were measured.

TABLE I Physical or Performance Method of the Present disclosure ColdMix Method Property Emulsifier A Emulsifier B Emulsifier C Emulsifier AEmulsifier B Emulsifier C Coating (%) 99 94 94 95 89 99 Specimen Height62.4 62.7 62.2 66.1 66.0 65.8 (mm) Compressive 3000 3100 3325 2100 14602000 Strength after 4 hours at 25° C. (lb-f)

A comparison of the respective bituminous compositions was made forthree critical physical and performance properties—coating,densification, and strength development. Compacted specimens prepared bymixing and compacting emulsion and aggregate at ambient temperatures(i.e., according to traditional cold mix methods) showed substantiallydifferent physical and performance properties than those exhibited bythe bituminous compositions made by the method of the presentdisclosure. These results are listed in Table 1.

As shown in Table 1, the bituminous compositions of the presentdisclosure had aggregate coating levels of 94% to 99%. The mixes gavecompacted bituminous compositions (pills) with heights ranging from 62.2to 62.7 mm after compaction, which were substantially denser than thecold mix pills. The same compacted bituminous compositions madeaccording to the method of the present disclosure exhibited compressivestrength (lb-f) values after storage at 25° C. four hours of 3,000-3,235lb-f, which was substantially stronger than that exhibited by the coldmix examples. As previously mentioned, this compressive strength value,obtained after only four hours of curing at ambient temperature, isreferred to herein as “early strength.”

The emulsion from Example 1 used in the evaluations shown in FIG. 1,contained 0.5% by total weight of bitumen emulsion (bwe) of emulsifier(tallow polyalkylenepolyamines) at 60% residue of PG64-22 bitumen. Thebitumen emulsions of the present disclosure exhibit high shearstabilities at the elevated temperatures of the present disclosure(i.e., about 50° C. to about 120° C.). FIG. 1 shows the effect ofexposing a bitumen emulsion (formulated and produced according to theteachings of this disclosure) to increasing shear rates using a TARheometer at varying temperatures. In these experiments, the shear ratewas increased from 0 to 1,000 seconds-inverse in 120 seconds. Becausehigh shear induced coalesce of the emulsion at 25° C., the instrumentexperienced torque overload. Upon lifting the rotor of the rheometer,black, coalesced bitumen was observed, and grains of large coalesceddroplets could be felt in what remained of the original liquid emulsion.At 80° C., the emulsion shows a smooth decrease in viscosity withincreasing shear rate.

EXAMPLE 2

The physical and performance properties of bituminous compositions madeusing the method of the present disclosure were also compared to theproperties of bitumen and aggregate mixes made according to traditionalhot mix asphalt methodologies. All bituminous compositions in thisexample contained commercially available, performance-grade PG70-22bitumen, and were prepared with a bitumen content of 4.8% by totalweight of the graded aggregate.

Bituminous compositions of the present disclosure were prepared by thefollowing procedure. Solvent-free bitumen emulsions were prepared usingtallow polyalkylenepolyamines emulsifier at 1.0% by total weight of thebitumen emulsion (bwe). The emulsifier was dissolved in warm water andtreated with hydrochloric acid solution to lower the pH to 2.0. Theaqueous solution of emulsifier(s) in water (called the “soap solution”)was heated to 55° C. and added to an Atomix colloid mill.

The bitumen employed in this example was a commercially available,performance-grade PG70-22. The bitumen was heated to 130° C. and addedto the Atomix colloid mill, wherein the soap solution and bitumenmixture was processed to produce bitumen emulsion. The bitumen contentof the finished bitumen emulsion was about 60-63% bwe. The bitumenemulsions were subsequently diluted with water to 53.3% bitumen contentprior to mixing with aggregate.

For bituminous compositions made in this example according to the methodof the present disclosure, the graded aggregate of Example 1 was heatedto about 80° C. in an oven while the bitumen emulsion was heated toabout 60° C. About 1,000 grams of heated graded aggregate were placed ina 1-gallon stainless steel bucket. To the 1,000 grams of aggregate at80° C. was added 90 g of 60° C. bitumen emulsion. The mixture wasstirred by hand for approximately 60 seconds to produce the bituminouscompositions containing about 4.8% bitumen by total weight of the gradedaggregate.

The resulting bitumen compositions (having a temperature in the range ofabout 60° C. to about 80° C.) were added immediately to a 100-mmdiameter gyratory compaction mold, which had been preheated to 60°C.-80° C. The bitumen compositions were then compacted using 30gyrations of a SHRP Pine gyratory compactor at 600 kPa pressure and agyration angle of 1.25°.

The compacted bituminous compositions were placed in a 25° C. oven andallowed to cure for four hours. After four hours of curing, the physicaland performance properties of the compacted and cured bituminouscompositions were measured.

For comparison purposes, a hot mix specimen having equivalent aggregategradation and bitumen content was made according to standard laboratoryprocedures for the preparation of hot mix bituminous compositions.Graded aggregate was prepared as in Example 1. About 1,000 grams ofgraded aggregate heated to 140° C. were placed in a 1-gallon stainlesssteel bucket. To the 1,000 grams of heated aggregate was added 48 gramsof a PG70-22 bitumen, which had been previously heated to 140° C. Themixture was stirred by hand for approximately 30 seconds to distributethe bitumen over the surface of the hot aggregate. The coated aggregatewas returned to the oven and heated until the temperature reached 140°C. The resulting hot mix bituminous composition was removed and stirreda second time by hand for 30 seconds, then transferred to a 100-mmgyratory compaction mold which had been previously heated to 140° C. Thegyratory compaction mold and bituminous composition were returned to the140° C. oven for 20 minutes. The hot mix bitumen composition was thencompacted using 30 gyrations of a SHRP Pine gyratory compactor at 600kPa pressure and a gyration angle of 1.25°.

The compacted hot mix bituminous compositions were placed in a 25° C.oven and allowed to cure for four hours. After four hours of curing, thephysical and performance properties of the compacted and cured hot mixbituminous compositions were measured.

A second compacted hot mix bituminous composition was prepared accordingto the aforementioned hot mix procedure except that the temperature usedin all mixing, heating, and compaction steps was 160° C. instead of 140°C.

For further comparison purposes, a cold mix bituminous composition wasproduced having equivalent aggregate gradation and bitumen content. Theprocedure for the production of the bituminous composition of thepresent disclosure noted above was followed for producing these cold mixbituminous compositions with the exception that the bitumen emulsion andthe graded aggregate were each at ambient room temperature (23° C.) whenmixed in the bucket.

The resulting cold mix bitumen compositions at ambient temperature wereadded immediately to a 100-mm diameter gyratory compaction mold, whichwas also at ambient temperature. The ambient-temperature bitumencompositions were then compacted using 30 gyrations of a SHRP Pinegyratory compactor at 600 kPa pressure and a gyration angle of 1.25°.

The compacted bitumen compositions were placed in a 25° C. oven andallowed to cure for four hours. After four hours of curing, the physicaland performance properties of the compacted and cured cold mixbituminous compositions were measured.

Standard volumetric procedures were used on all mixes (those made by themethod of the present disclosure, as well as the hot mixes and coldmixes) to determine air voids (Pa). Table II shows that the mixes madeby the method of the present disclosure compacted more effectively thaneither the hot mixes or the cold mixes. Table II further shows that thebituminous emulsions made by the method of the present disclosure gaveair voids (Pa) that were comparable to those of the hot mix specimens,and substantially improved above those of the cold mix specimen. Allspecimens were fully coated (i.e., percent coating greater than 99%).

TABLE II Physical and PG70-22 PG70-22 PG70-22 Performance Cold Mix HotMix Hot Mix Method of Properties (20-23° C.) (140° C.) (160° C.) thePresent Disclosure Average Pill 64.8 +/− 0.6 63.7 +/− 0.0 63.7 +/− 0.462.6 +/− 0.5 Height (mm) and Std. Dev. Early Cure: 1050 4600 4800 2450Compressive Strength after 4 hours at 25° C. (lb-f) Full Cure: 4125 46505100 4875 Compressive Strength after 24 hours at 60° C. (lb-f) % AirVoids, Pa 10.24 8.22 8.70 6.86

EXAMPLE 3

Bituminous compositions of the present disclosure were produced andcompacted using the procedure of Example 2. Solvent-free bitumenemulsions were prepared using tallow polyalkylenepolyamines emulsifierat 0.5% by total weight of the bitumen emulsion (bwe). The bitumenemployed in this example was commercially available, performance-gradePG64-22 bitumen modified with styrene-butadiene-styrene (SBS) polymer.All of the bituminous compositions in this example contained thismodified PG64-22 bitumen, and each was prepared with a bitumen contentof 4.8% by total weight of the graded aggregate.

For comparison purposes, a hot mix bituminous composition havingequivalent aggregate gradation and bitumen content to the above-notedbituminous composition was produced and compacted using the procedure ofExample 2.

For further comparison purposes a cold mix bituminous composition wasalso produced having equivalent aggregate gradation and bitumen content.The procedure for the production of the bituminous composition of thepresent disclosure noted above was followed for producing these cold mixbituminous compositions with the exception that the bitumen emulsion andthe graded aggregate were each at ambient room temperature (23° C.) whenmixed in the bucket.

TABLE III SBS SBS Method of Physical and Cold Mix Hot Mix the PresentPerformance Properties (20-23° C.) (160° C.) Disclosure Average PillHeight 64.8 +/− 0.1 63.8 +/− 0.4 62.6 +/− 0.5 (mm) and Std. Dev. EarlyCure: 1350 6400 3400 Compressive Strength after 4 hours at 25° C. (lb-f)Full Cure: 4875 Not run 5750 Compressive Strength after 24 hours at 60°C. (lb-f) % Air Voids, Pa 8.86 Not run 4.92

The physical and performance properties of the respective compacted andcured bituminous compositions were measured, and the results are shownin Table III.

EXAMPLE 4

Bituminous compositions of the present disclosure were produced andcompacted using the procedure of Example 2. Solvent-free bitumenemulsions were prepared using alkyl alkylenepolyamine emulsifiers atdosages ranging from 1.0% to 0.5% by total weight of the bitumenemulsion (bwe). The bitumen employed in this example was a commerciallyavailable, performance-grade unmodified PG64-22. All of the bituminouscompositions in this example contained this PG64-22 bitumen, and eachwas prepared with a bitumen content of 4.8% by total weight of thegraded aggregate.

For comparison purposes, cold mix bituminous compositions were producedhaving equivalent aggregate gradation and bitumen content. The procedurefor the production of the bituminous composition of the presentdisclosure noted above was followed for producing these cold mixbituminous compositions with the exception that the bitumen emulsion andthe graded aggregate were each at ambient room temperature (23° C.) whenmixed in the bucket.

The physical and performance properties of the respective compacted andcured bituminous compositions were measured, and the results are shownin Table IV.

As shown in Table IV, the pills made with the bituminous compositions ofthe present disclosure exhibited compressive strength values aftercuring at 25° C. for four hours which were 86%-163% stronger than theidentically formulated, emulsion-based cold mix bituminous compositionsmade and compacted at ambient laboratory conditions. Additionally, thebituminous compositions of the present disclosure showed substantiallyimproved densification when compared to the cold mix compositions.Likewise, the present bituminous compositions had calculated air voids(Pa) 2.76 to 3.72 percent points lower than the Pa values of thecomparable cold mix specimens (each mm of pill height corresponds toroughly 1.2% air content in the specimen).

TABLE IV Cold mix Present Disclosure Compressive Increase in CompressiveStrength after Densification - Strength after Increase in EmulsifierPill Curing 4 hours Pill Change in Pa Curing 4 hours StrengthDevelopment - Dosage Height at 25° C. Height vs cold mix at 25° C.Percent change vs (%) (mm) (lb-f) (mm) (delta Pa) (lb-f) cold mix 1.065.5 850 62.6 −3.48 2200 159% 0.75 66.0 950 62.9 −3.72 2500 163% 0.565.8 1400 63.5 −2.76 2600 86%

EXAMPLE 5

Bituminous compositions of the present disclosure were produced andcompacted using the procedure of Example 2. Solvent-free bitumenemulsions were prepared using tallow polyalkylenepolyamine emulsifier atdosages ranging from 1.0% to 0.5% by total weight of the bitumenemulsion (bwe). The bitumen employed in this example was a commerciallyavailable, performance-grade PG70-22. All of the bituminous compositionsin this example contained this PG70-22 bitumen, and each was preparedwith a bitumen content of 4.8% by total weight of the graded aggregate.

For comparison purposes, cold mix bituminous compositions were producedhaving equivalent aggregate gradation and bitumen content. The procedurefor the production of the bituminous composition of the presentdisclosure noted above was followed for producing these cold mixbituminous compositions with the exception that the bitumen emulsion andthe graded aggregate were each at ambient room temperature (23° C.) whenmixed in the bucket.

The physical and performance properties of the respective compacted andcured bituminous compositions were measured, and the results are shownin Table V below.

TABLE V Cold mix Present Disclosure Compressive Compressive EmulsifierPill Height Strength Pill Height Strength Dosage (%) (mm) (lb-f) (mm)(lb-f) 1.0 63.8 1300 62.1 2850 0.75 65.6 1550 62.4 3750 0.5 66.5 200063.1 3050

As shown in Table V, the pills made with the bituminous compositions ofthe present disclosure exhibited compressive strength values aftercuring at 25° C. for four hours which were 52%-142% stronger than theidentically formulated, emulsion-based cold mix bituminous compositionsmade and compacted at ambient laboratory conditions. Additionally, thebituminous compositions of the present disclosure showed substantiallyimproved compaction compared to the analogous cold mix compositions asmeasured by the heights of the pill specimens.

EXAMPLE 6

Bituminous compositions of the present disclosure were produced andcompacted using the procedure of Example 2. Solvent-free bitumenemulsions were prepared using tallow polyalkylenepolyamine emulsifier atdosages ranging from 1.0% to 0.5% by total weight of the bitumenemulsion (bwe). The bitumen employed in this example was a commerciallyavailable, performance-grade PG64-22 bitumen modified withstyrene-butadiene-styrene block copolymer. All of the bituminouscompositions in this example contained this modified PG64-22 bitumen,and each was prepared with a bitumen content of 4.8% by total weight ofthe graded aggregate.

For comparison purposes, cold mix bituminous compositions were producedhaving equivalent aggregate gradation and bitumen content. The procedurefor the production of the bituminous composition of the presentdisclosure noted above was followed for producing these cold mixbituminous compositions with the exception that the bitumen emulsion andthe graded aggregate were each at ambient room temperature (23° C.) whenmixed in the bucket.

The physical and performance properties of the respective compacted andcured bituminous compositions were measured, and the results are shownin Table VI below.

TABLE VI Cold mix Present Disclosure Compressive Compressive EmulsifierPill Height Strength Pill Height Strength Dosage (%) (mm) (lb-f) (mm)(lb-f) 1.0 65.2 1200 63.0 3050 0.75 65.6 1450 62.9 2800 0.5 66.5 165063.2 2650

As shown in Table VI, the pills made with the bituminous compositions ofthe present disclosure exhibited compressive strength values aftercuring at 25° C. for four hours which were stronger than the identicallyformulated, emulsion-based cold mix bituminous compositions made andcompacted at ambient laboratory conditions. Additionally, the bituminouscompositions of the present disclosure showed substantially improvedcompaction compared to the analogous cold mix compositions as measuredby the heights of the pill specimens.

EXAMPLE 7

Bituminous compositions of the present disclosure were produced andcompacted using the procedure of Example 2. Solvent-free bitumenemulsions were prepared using tallow polyalkylenepolyamine emulsifier at0.5% by total weight of the bitumen emulsion (bwe). The bitumen employedin this example was a commercially available, performance-grade PG64-22bitumen modified via the addition of styrene-butadiene-rubber (SBR). Twolevels of bitumen modification were examined: 1% SBR bwe and 3% SBR bwe.All of the bituminous compositions in this example contained modifiedPG64-22 bitumen, and each was prepared with a bitumen content of 4.8% bytotal weight of the graded aggregate.

For comparison purposes, cold mix bituminous compositions were producedhaving equivalent aggregate gradation and bitumen content. The procedurefor the production of the bituminous composition of the presentdisclosure noted above was followed for producing these cold mixbituminous compositions with the exception that the bitumen emulsion andthe graded aggregate were each at ambient room temperature (23° C.) whenmixed in the bucket.

The physical and performance properties of the respective compacted andcured bituminous compositions were measured, and the results are shownin Table VII below.

TABLE VII Cold mix Present Disclosure Compressive Compressive SBRmodification Pill Height Strength Pill Height Strength level (mm) (lb-f)(mm) (lb-f) 1% bwe 66.8 950 63.2 3050 3% bwe 67.1 900 63.4 2800

As shown in Table VII, the pills made with the bituminous compositionsof the present disclosure made at 1% SBR bwe exhibited compressivestrength values after curing at 25° C. for four hours which were over220% higher than the identically formulated, emulsion-based cold mixbituminous compositions made and compacted at ambient laboratoryconditions, while the pills made at 3% SBR bwe exhibited a 210% increasein compressive strength over the corresponding cold mix pills.Additionally, the bituminous compositions of the present disclosureshowed substantially improved compaction compared to the analogous coldmix compositions as measured by the heights of the pill specimens.

EXAMPLE 8

Bituminous compositions of the present disclosure were produced andcompacted using the procedure of Example 2. Solvent-free bitumenemulsions were prepared using modified tall oil condensate ofpolyethylene polyamine at dosages ranging from 1.0% to 1.5% by totalweight of the bitumen emulsion (bwe). Three commercially available,performance grade bitumen types were employed in this example: aPG64-22, a PG78-28, and a styrene-butadiene-styrene (SBS) modifiedPG64-22. Each of the bituminous compositions was prepared with a bitumencontent of 4.8% by total weight of the graded aggregate.

The bitumen emulsion used in the evaluations shown in FIG. 2, producedin Example 7 below, contains 1.0% bwe of emulsifier (modified tall oilfatty acid condensate of polyethylene polyamine).

For comparison purposes, cold mix bituminous compositions were producedhaving equivalent aggregate gradation and bitumen content. The procedurefor the production of the bituminous composition of the presentdisclosure noted above was followed for producing these cold mixbituminous compositions with the exception that the bitumen emulsion andthe graded aggregate were each at ambient room temperature (23° C.) whenmixed in the bucket.

TABLE VIII Cold mix Present Disclosure Emulsifier Pill CompressiveCompressive Bitumen Dosage Height Strength Pill Height Strength Type (%)(mm) (lb-f) (mm) (lb-f) PG64-22 1.0 65.5 800 62.3 2450 1.5 62.6 975 62.51950 PG78-28 1.5 63.6 1600 62.8 3600 SBS- 1.0 65.2 1150 62.8 2700modified 1.5 63.1 1175 63.0 2850

The physical and performance properties of the respective compacted andcured bituminous compositions were measured, and the results are shownin Table VIII.

As shown in Table VIII, the pills made with the bituminous compositionsof the present disclosure exhibited compressive strength values aftercuring at 25° C. for four hours which were stronger than the identicallyformulated, emulsion-based cold mix bituminous compositions made andcompacted at ambient laboratory conditions. Additionally, the bituminouscompositions of the present disclosure showed improved compactioncompared to the analogous cold mix compositions as measured by theheights of the pill specimens.

FIG. 2 shows comparable results using a different emulsion. The bitumenemulsion used in the evaluations shown in FIG. 2, contained 1.0% bwe ofemulsifier (modified tall oil fatty acid condensate of polyethylenepolyamine) at 60% residue of PG64-22 bitumen (a performance-gradebitumen modified with a styrene-butadiene-styrene block copolymer).Again, at 25° C., the analysis showed the irregular viscosity build asthe shear rate increased from 0 to 1,000 seconds-inverse. At 60° C., theviscosity steadily decreased as the shear rate (and shear stress)increased.

EXAMPLE 9

Bituminous compositions of the present disclosure were produced andcompacted using the procedure of Example 2. Solvent-free bitumenemulsions were prepared using as an emulsifier modified and unmodifiedC16-C18 fatty acid condensate of polyethylene polyamine at dosagesranging from 1.0% to 1.5% by total weight of the bitumen emulsion (bwe).Three commercially available, performance grade bitumen types wereemployed in this example: a PG64-22, a PG70-22, and astyrene-butadiene-styrene (SBS) modified PG64-22. Each of the bituminouscompositions was prepared with a bitumen content of 4.8% by total weightof the graded aggregate.

For comparison purposes, cold mix bituminous compositions were producedhaving equivalent aggregate gradation and bitumen content. The procedurefor the production of the bituminous composition of the presentdisclosure noted above was followed for producing these cold mixbituminous compositions with the exception that the bitumen emulsion andthe graded aggregate were each at ambient room temperature (23° C.) whenmixed in the bucket.

The physical and performance properties of the respective compacted andcured bituminous compositions were measured, and the results are shownin Table IX below.

TABLE IX Cold mix Present Disclosure Emulsifier Pill CompressiveCompressive Bitumen Dosage Height Strength Pill Height Strength Type (%)(mm) (lb-f) (mm) (lb-f) PG64-22 1.0 65.6 900 62.9 1800 0.75 65.7 90062.7 1800 PG70-22 0.75 65.9 1350 62.0 2600 SBS- 0.50 66.7 1500 64.0 3700modified

As shown in Table IX, the pills made with the bituminous compositions ofthe present disclosure exhibited compressive strength values aftercuring at 25° C. for four hours which were stronger than the identicallyformulated, emulsion-based cold mix bituminous compositions made andcompacted at ambient laboratory conditions. Additionally, the bituminouscompositions of the present disclosure showed substantially improvedcompaction compared to the analogous cold mix compositions as measuredby the heights of the pill specimens.

FIG. 3 also shows comparable results in yet another differentlyformulated bitumen emulsion. The bitumen emulsion used in theevaluations shown in FIG. 3, contained 0.75% bwe of emulsifier (modifiedand unmodified C16-C18 fatty acid condensate of polyethylene polyamine)at 60% residue of PG70-22 bitumen.

EXAMPLE 10

Bituminous compositions of the present invention were produced andcompacted using the procedure of Example 2. Solvent-free bitumenemulsions were prepared using alkyl quaternary amines emulsifier at0.75% by total weight of the bitumen emulsion (bwe). Three commerciallyavailable, performance grade bitumen types were employed in thisexample: a PG64-22, a PG70-22, and a styrene-butadiene-styrene (SBS)modified PG64-22. Each of the bituminous compositions was prepared witha bitumen content of 4.8% by total weight of the graded aggregate.

For comparison purposes, cold mix bituminous compositions were producedhaving equivalent aggregate gradation and bitumen content. The procedurefor the production of the bituminous composition of the presentinvention noted above was followed for producing these cold mixbituminous compositions with the exception that the bitumen emulsion andthe graded aggregate were each at ambient room temperature (23° C.) whenmixed in the bucket.

The physical and performance properties of the respective compacted andcured bituminous compositions were measured, and the results are shownin Table X below.

TABLE X Cold mix Present Invention Compressive Compressive Pill HeightStrength Pill Height Strength Bitumen Type (mm) (lb-f) (mm) (lb-f)PG64-22 63.5 1150 62.7 2200 PG70-22 63.5 1100 63.2 2500 SBS-modified64.3 1250 63.5 2150

As shown in Table X, the pills made with the bituminous compositions ofthe present invention exhibited compressive strength values after curingat 25° C. for four hours which were stronger than the identicallyformulated, emulsion-based cold mix bituminous compositions made andcompacted at ambient laboratory conditions. Additionally, the bituminouscompositions of the present invention showed improved compactioncompared to the analogous cold mix compositions as measured by theheights of the pill specimens.

EXAMPLE 11

Bituminous compositions of the present invention were produced andcompacted using the procedure of Example 2. Solvent-free bitumenemulsions were prepared using as an emulsifier a blend of tallowpolyalkylenepolyamine and aminated natural resins from the general classknown as quebracho resins at 1.5% by total weight of the bitumenemulsion (bwe). Two commercially available, performance grade bitumentypes were employed in this example: a PG64-22 and astyrene-butadiene-styrene (SBS) modified PG64-22. Each of the bituminouscompositions was prepared with a bitumen content of 4.8% by total weightof the graded aggregate.

For comparison purposes, cold mix bituminous compositions were producedhaving equivalent aggregate gradation and bitumen content. The procedurefor the production of the bituminous composition of the presentinvention noted above was followed for producing these cold mixbituminous compositions with the exception that the bitumen emulsion andthe graded aggregate were each at ambient room temperature (23° C.) whenmixed in the bucket.

The physical and performance properties of the respective compacted andcured bituminous compositions were measured, and the results are shownin Table XI below.

TABLE XI Cold mix Present Invention Compressive Compressive Pill HeightStrength Pill Height Strength Bitumen Type (mm) (lb-f) (mm) (lb-f)PG64-22 64.8 850 62.9 1975 SBS-modified 64.0 1100 62.7 2450

As shown in Table XI, the pills made with the bituminous compositions ofthe present invention exhibited compressive strength values after curingat 25° C. for four hours which were stronger than the identicallyformulated, emulsion-based cold mix bituminous compositions made andcompacted at ambient laboratory conditions. Additionally, the bituminouscompositions of the present invention showed improved compactioncompared to the analogous cold mix compositions as measured by theheights of the pill specimens.

EXAMPLE 12

A bituminous composition of the present invention was produced andcompacted using the procedure of Example 2. A solvent-free bitumenemulsion was prepared using as an emulsifier a blend of 0.2% by totalweight of the bitumen emulsion (bwe) of tallow polyalkylenepolyaminesand 0.8% bwe of polyethylenepolyamine condensate of modified andunmodified fatty acids. The bitumen employed in this example was acommercially available, performance-grade PG64-22 bitumen. Each of thebituminous compositions in this example contained PG64-22 bitumen, andwas prepared with a bitumen content of 4.8% by total weight of thegraded aggregate.

For comparison purposes, a cold mix bituminous composition was producedhaving equivalent aggregate gradation and bitumen content. The procedurefor the production of the bituminous composition of the presentinvention noted above was followed for producing the cold mix bituminouscomposition with the exception that the bitumen emulsion and the gradedaggregate were each at ambient room temperature (23° C.) when mixed inthe bucket.

TABLE XII Cold mix Present Invention Compressive Compressive Pill HeightStrength Pill Height Strength Bitumen Type (mm) (lb-f) (mm) (lb-f)PG64-22 66.3 850 63.1 2400

The physical and performance properties of the respective compacted andcured bituminous compositions were measured, and the results are shownin Table XII.

As shown in Table XII, the pills made with the bituminous composition ofthe present invention exhibited a compressive strength value aftercuring at 25° C. for four hours which was stronger than the identicallyformulated, emulsion-based cold mix bituminous composition made andcompacted at ambient laboratory conditions. Additionally, the bituminouscomposition of the present invention showed improved compaction comparedto the analogous cold mix composition as measured by the heights of thepill specimens.

EXAMPLE 13

Bituminous compositions of the present invention were prepared by thefollowing procedure. Solvent-free bitumen emulsions were prepared usingtallow polyalkylenepolyamines emulsifier at 0.5% by total weight of thebitumen emulsion (bwe). The emulsifier was dissolved in warm water andtreated with hydrochloric acid solution to lower the pH to 2.0. Theaqueous solution of emulsifier(s) in water (called the “soap solution”)was heated to 55° C. and added to an Atomix colloid mill.

The bitumen employed in this example was a commercially available,performance-grade PG64-22. The bitumen was heated to 130° C. and addedto the Atomix colloid mill, wherein the soap solution and bitumenmixture was processed to produce bitumen emulsion. The bitumen contentof the finished bitumen emulsion was about 60-63% bwe. The bitumenemulsions were subsequently diluted with water to 53.3% bitumen contentprior to mixing with aggregate.

The graded aggregate of Example 1 was heated to about 80° C. in an ovenwhile the bitumen emulsion was heated to about 60° C. About 1,000 gramsof heated graded aggregate were placed in a 1-gallon stainless steelbucket. To the 1,000 grams of aggregate at 80° C. was added 90 g of 60°C. bitumen emulsion. The mixture was stirred by hand for approximately60 seconds to produce the bituminous compositions containing about 4.8%bitumen by total weight of the graded aggregate.

One of the resulting bitumen compositions (having a temperature in therange of about 60° C. to about 80° C.) was added immediately to a 100-mmdiameter gyratory compaction mold, which had been preheated to 60°C.-80° C. The bitumen compositions were then compacted using 30gyrations of a SHRP Pine gyratory compactor at 600 kPa pressure and agyration angle of 1.25°. The compacted bituminous composition wassubsequently placed in a 25° C. oven and allowed to cure for four hours.After four hours of curing, the physical and performance properties ofthe compacted and cured bituminous composition were measured.

The other resulting bitumen composition (having a temperature in therange of about 60° C. to about 80° C.) was immediately loaded and sealedin a polyethylene bag and placed in an oven having a temperaturemaintained at 60° C. After three hours, the bitumen composition (havinga temperature of about 60° C.) was removed from the oven and immediatelyloaded into a 100-mm diameter gyratory compaction mold, which had beenpreheated to 60° C. The bitumen composition was then compacted using 30gyrations of a SHRP Pine gyratory compactor at 600 kPa pressure and agyration angle of 1.25°. The compacted bituminous composition was placedin a 25° C. oven and allowed to cure for four hours. After four hours ofcuring, the physical and performance properties of the compacted andcured bituminous composition were measured.

The physical and performance properties of the respective compacted andcured bituminous compositions were measured, and the results showed thatstorage did not adversely affect the coating, compactability, or earlystrength of the bituminous compositions. This indicates that theworkability of the bituminous compositions was not compromised ordecreased by storage.

EXAMPLE 14

Bituminous compositions of the present invention were prepared by thefollowing procedure. Solvent-free bitumen emulsions were prepared usingtallow polyalkylenepolyamines emulsifier at 0.5% by total weight of thebitumen emulsion (bwe). The emulsifier was dissolved in warm water andtreated with hydrochloric acid solution to lower the pH to 2.0. Theaqueous solution of emulsifier(s) in water (called the “soap solution”)was heated to 55° C. and added to an Atomix colloid mill.

The bitumen employed in this example was a commercially available,performance-grade styrene-butadiene-styrene (SBS) modified PG64-22. Thebitumen was heated to 130° C. and added to the Atomix colloid mill,wherein the soap solution and bitumen mixture was processed to producebitumen emulsion. The bitumen content of the finished bitumen emulsionwas about 60-63% bwe. The bitumen emulsions were subsequently dilutedwith water to 53.3% bitumen content prior to mixing with aggregate.

The graded aggregate of Example 1 was heated to about 80° C. in an ovenwhile the bitumen emulsion was heated to about 60° C. About 1,000 gramsof heated graded aggregate were placed in a 1-gallon stainless steelbucket. To the 1,000 grams of aggregate at 80° C. was added 90 g of 60°C. bitumen emulsion. The mixture was stirred by hand for approximately60 seconds to produce the bituminous compositions containing about 4.8%bitumen by total weight of the graded aggregate.

One of the resulting bitumen compositions (having a temperature in therange of about 60° C. to about 80° C.) was added immediately to a 100-mmdiameter gyratory compaction mold, which had been preheated to 60°C.-80° C. The bitumen compositions were then compacted using 30gyrations of a SHRP Pine gyratory compactor at 600 kPa pressure and agyration angle of 1.25°. The compacted bituminous composition wassubsequently placed in a 25° C. oven and allowed to cure for four hours.After four hours of curing, the physical and performance properties ofthe compacted and cured bituminous composition were measured.

The other resulting bitumen composition (having a temperature in therange of about 60° C. to about 80° C.) was immediately loaded into apolyethylene bag and placed in an oven having a temperature maintainedat 60° C. After 21 hours, the bitumen composition (having a temperatureof about 60° C.) was removed from the oven and immediately loaded into a100-mm diameter gyratory compaction mold, which had been preheated to60° C. The bitumen composition was then compacted using 30 gyrations ofa SHRP Pine gyratory compactor at 600 kPa pressure and a gyration angleof 1.25°. The compacted bituminous composition was placed in a 25° C.oven and allowed to cure for four hours. After four hours of curing, thephysical and performance properties of the compacted and curedbituminous composition were measured.

The physical and performance properties of the respective compacted andcured bituminous compositions were measured, and the results showed thatstorage did not adversely affect the coating, compactability, or earlystrength of the bituminous compositions. This indicates that theworkability of the bituminous compositions was not compromised ordecreased by storage.

EXAMPLE 15

Solvent-free bitumen emulsions suitable for use in the production ofbituminous compositions of the present invention were prepared by thefollowing procedure. A series of solvent-free bitumen emulsions wereprepared using tallow polyalkylenepolyamines emulsifier at 1.0% by totalweight of the bitumen emulsion (bwe). The emulsifier was dissolved inwarm water and treated with hydrochloric acid solution to lower the pHto 2.0. The aqueous solution of emulsifier in water (called the “soapsolution”) was heated to 55° C. and added to an Atomix colloid mill.

Four performance grade bitumen types were employed in this example inproduce the series of bitumen emulsions. A commercially availablePG64-22 and a commercially available styrene-butadiene-styrene (SBS)modified PG64-22 was used. Also, a PG64-22 bitumen modified via theaddition of styrene-butadiene-rubber (SBR) at either 1% SBR bwe or 3%SBR bwe were employed. The respective bitumen were heated to 130° C. andadded to the Atomix colloid mill, wherein the soap solution and bitumenmixture was processed to produce bitumen emulsion.

As noted in Tables XVI-XIX below, the resulting bitumen emulsions showsubstantially unchanged particle size distributions when held atelevated temperatures for a period of time. Table XIII shows that withthe unmodified bitumen the starting mean particle diameter (mv) waslower than in the case of the SBS-modified bitumen (Table XIV), as theSBS-modified bitumens give relatively high mean particle size diametersas well as high overall particle size distributions (as reflected in90th percentile particle diameter).

TABLE XIII Particle Size Distribution at Elevated Temperature Time atUnmodified Bitumen Emulsion Indicated Storage Temperatures Temp. 25° C.60° C. 80° C. (hours) mv <90% Mv <90% mv <90% 0 6.7 12.6 Not Not Not Notrun run run run 24 6.5 12.2 6.7 12.9 6.8 13.1 48 6.9 13.1 6.4 12.1 7.013.8 120 7.1 14.2 5.7 10.6 4.8  7.4

TABLE XIV Particle Size Distribution At Elevated Temperature Time atSBS-Modified Bitumen Emulsion Indicated Storage Temperatures Temp. 25°C. 60° C. 80° C. (hours) mv <90% Mv <90% mv <90% 0 5.5 16.0 8.9 28.013.0 34.6 24 5.6 16.3 7.1 20.8 7.1 21.6 48 8.1 23.2 10.7 28.0 6.6 19.4120 7.9 22.6 9.2 24.8 9.0 23.9

TABLE XV Particle Size Distribution At Elevated Temperature Time at 1%SBR-Modified Bitumen Emulsion Indicated Storage Temperatures Temp. 25°C. 60° C. 80° C. (hours) Mv <90% Mv <90% mv <90% 0 9.3 20.5 — — — — 487.6 14.7 9.5 20.8 — — 72 9.1 19.3 6.9 12.5 6.7 11.9 120 8.8 18.1 8.216.9 10.8 57.1

TABLE XVI Particle Size Distribution At Elevated Temperature Time at 3%SBR-Modified Bitumen Emulsion Indicated Storage Temperatures Temp. 25°C. 60° C. 80° C. (hours) Mv <90% Mv <90% mv <90% 0 9.1 19.2 — — — — 486.6 11.5 8.4 17.0 — — 72 5.9 9.3 6.8 12.6 7.4 13.7 120 6.7 11.9 11.323.7 18.2 43.7

EXAMPLE 16

Bituminous compositions of the present invention were also produced intypical full-scale operations using parallel flow drum plants infull-scale construction projects conducted in the Republic of SouthAfrica, where many new asphalt paving technologies have been developedin recent years. In the first full-scale construction operation,solvent-free bitumen emulsions were prepared using 60/70 bitumen andemulsifiers consisting of blends of polyalkylenepolyamine condensate ofmodified and unmodified fatty acids and one or more tallowpolyalkylenepolyamines. Percentages of the polyalkylenepolyaminecondensate of modified and unmodified fatty acids ranged from 0-1.0% andpercentages of the tallow polyalkylenepolyamines ranged from 0-1.0%,both by weight of the emulsion. The emulsifier was dissolved in warmwater and treated with hydrochloric acid solution to lower the pH to2.0. The aqueous solution of emulsifier(s) in water (called the “soapsolution”) was heated to 55° C. and added to an Atomix-type colloidmills. Aggregate was a 9.5 mm nominal andesite with mine tailings. TheP-200 content in the aggregate was 7.5%. Emulsion was diluted to 50%bitumen residue prior to injection into a parallel drum plant.Sufficient emulsion was pumped into the drum mixer to yield a bituminouscomposition having 5.4% bitumen by weight of the aggregate. No dust wasemitted from the dust collector on the drum mixer during the course offull-scale production of the bituminous composition. The temperature ofsamples of the production-scale bituminous composition according to thisinvention ranged between 80-120° C. The bituminous mixture was stored ina conventional, unheated hot-mix asphalt storage silo. After roughlyeighteen hours of silo storage, the bituminous composition wasdischarged to standard 15-ton dump trucks. The trucks discharged themixture to a standard hot mix paver, which distributed the mix in depthsof 0.75 to 3 inches and widths of eight to twelve feet wide, accordingto standard lay-down construction practices. No sticking of thebituminous composition was observed in the beds of the dump trucks or inthe moving parts or screed of the hot-mix paver. Three-point steel wheelrollers (13-ton) were used as break-down compacters, followed bypneumatic rollers (20-ton) for finishing compaction. Weather conditionsat the time of lay-down, construction, and compaction were roughly 18°C. with a slight drizzle and wind velocity of 7-11 miles per hour.Transverse or longitudinal seams were barely visible, no raveling,rutting, or cracking was observed one hour after production or after 14months of service under heavy daily traffic consisting of gravel andhot-mix dump trucks.

EXAMPLE 17

Bituminous compositions of the present invention were also produced on amanufacturing scale in parallel flow drum plants in a second fieldproject the Republic of South Africa, where many new asphalt pavingtechnologies have been developed. In the second full-scale constructionjob, solvent-free bitumen emulsions were prepared using 80/100 bitumenand emulsifiers consisting of blends of polyalkylenepolyamine condensateof modified and unmodified fatty acids and one or more tallowpolyalkylenepolyamines. Percentages of the polyalkylenepolyaminecondensate of modified and unmodified fatty acids ranged from 0-0.30%and percentages of the tallow polyalkylenepolyamines ranged from0-0.30%, both by weight of the emulsion. The emulsifier was dissolved inwarm water and treated with hydrochloric acid solution to lower the pHto 2.0. The aqueous solution of emulsifier(s) in water (called the “soapsolution”) was heated to 55° C. and added to an Atomix-type colloidmills. Aggregate was a 19-mm nominal basalt. The P-200 content in theaggregate was roughly 7.0%. Emulsion was produced at 68% bitumenresidue. Sufficient emulsion was pumped into the drum mixer to yield abituminous composition having 5.0% bitumen by weight of the aggregate.No dust was emitted from the dust collector on the drum mixer during thecourse of full-scale production of the bituminous composition. Thetemperature of samples of the production-scale bituminous compositionaccording to this invention ranged between 60-120° C. The bituminousmixture was stored briefly in a conventional, unheated hot-mix asphaltstorage silo before being metered to standard 15-ton dump trucks. Thetrucks discharged the mixture to a standard hot mix paver, whichdistributed the mix in depths of 0.75 to 2 inches and widths of eight toten feet wide, according to standard lay-down construction practices. Nosticking of the bituminous composition was observed in the beds of thedump trucks or in the moving parts or screed of the hot-mix paver. Atandem steel wheel roller (13-ton) was used as break-down compacters,followed by pneumatic rollers (20-ton) for finishing compaction. Weatherconditions at the time of lay-down, construction, and compaction wereroughly 15-20° C. Traffic was opened in less than one hour of completingthe compaction. Cores were taken after roughly 18 hours of service.Nuclear gauge densities averaged 96.2% of Gmm, as targeted.

Many modifications and variations of the present invention will beapparent to one of ordinary skill in the art in light of the aboveteachings. It is therefore understood that the scope of the invention isnot to be limited by the foregoing description, but rather is to bedefined by the claims appended hereto.

1. A bituminous composition for surface paving, at a temperature of50-140° C. comprising: (a) solvent-free, oil-in-water bitumen emulsionin an amount from about 2% to about 10% by total weight of thebituminous composition, wherein the oil-in-water bitumen emulsioncomprises: (i) bitumen in an amount from about 50% to about 75% by totalweight of the bitumen emulsion, (ii) at least one active emulsifier inan amount from about 0.05% to about 2.0% by total weight of the bitumenemulsion, and (iii) water in an amount to complete the emulsion; and (b)aggregate in an amount from about 90% to about 98% by total weight ofthe bituminous composition; and wherein the bituminous composition is inan absence of bitumen having a penetration number of more than 220 dmmas determined according to an ASTM standard method D5 at 25° C., andwherein the bituminous composition has a temperature range of about 50°C. to 140° C.
 2. The composition of claim 1, wherein the bitumenemulsion comprises the bitumen in an amount range from about 60.0% toabout 70.0% by total weight of the emulsion.
 3. The composition of claim1, wherein the bitumen emulsion comprises the emulsifier in an amountrange from about 0.08% to about 0.75% by total weight of the emulsion.4. The composition of claim 1, wherein the bitumen emulsion comprises amember selected from the group consisting of naturally occurringbitumens, bitumen from crude oil, bitumen from petroleum pitch, bitumenfrom coal tar, sulfur-modified bitumen, acid-modified bitumen, andcombinations thereof.
 5. The composition of claim 1, wherein the bitumenemulsion comprises a bitumen modified with at least one member selectedfrom the group consisting of natural rubbers, synthetic rubbers,plastomers, thermoplastic resins, thermosetting resins, elastomers,styrene-butadiene-styrene, styrene-butadiene-rubber, polyisoprene,polybutylenes, butadiene-styrene rubbers, vinyl polymers, ethylene vinylacetate, and combinations thereof.
 6. The composition of claim 1,wherein the bitumen emulsion further comprises a member selected fromthe group consisting of styrene-butadiene rubber latex, polyisoprenelatex, neoprene, associative thickeners, starch, salt, and combinationsthereof.
 7. The composition of claim 1, wherein the emulsifier comprisesa member selected from the group consisting of amphoteric emulsifiers,cationic emulsifiers, nonionic emulsifiers and combinations thereof. 8.The composition of claim 7, wherein the amphoteric emulsifier comprisesa member selected from the group consisting of sodium C-12 to C-24 alkylamidopropyl halide methyl carboxylate betaines, potassium C-12 to C-24alkyl amidopropyl halide methyl carboxylate betaines, lithium C-12 toC-24 alkyl amidopropyl halide phosphate betaines, sodium C-12 to C-24alkyl amidopropyl halide phosphate betaines, potassium C-12 to C-24alkyl amidopropyl halide phosphate betaines, lithium C-12 to C-24 alkylamidopropyl halide sulphate betaines, sodium C-12 to C-24 alkylamidopropyl halide sulphate betaines, and potassium C-12 to C-24 alkylamidopropyl halide sulphate betaines, lithium C-12 to C-24 alkylamidopropyl halide methyl carboxylate betaines, C-12 to C-24 fattyimidoamines, rosin imidoamines, and combinations thereof.
 9. Thecomposition of claim 7, wherein the cationic emulsifier comprises amember selected from the group consisting of C-12 to C-24 fattyimidazolines; C-12 to C-24 fatty imidoamines; rosin imidoamines; C-12 toC-24 fatty amidoamines; rosin amidoamines; C-12 to C-24 alkylmonoamines; C-12 to C-24 alkyl polypropylene polyamines; C-12 to C-24alkyl monoamine polyoxyethylene; C-12 to C-24 alkyl monoaminepolyoxypropylene; C-12 to C-24 alkyl polypropylene monoaminespolyoxyethylene; C-12 to C-24 alkyl polypropylene monoaminespolyoxypropylene; C-12 to C-24 alkyl aryl monoamines; C-12 to C-24 alkylaryl polypropylene polyamines; C-12 to C-24 quaternary amines; C-12 toC-24 alkyl ether amines; C-12 to C-24 alkylether polyamines; C-12 toC-24 alkyl polypropylene polyamine N-oxides; amine derivatives oftannins; amine derivatives of phenolic resins; amine derivatives oflignins; amine-modified polyacrylates; and combinations thereof.
 10. Thecomposition of claim 1, wherein the aggregate comprises a memberselected from the group consisting of dense-graded aggregate, gap-gradedaggregate, open-graded, stone-matrix aggregate, reclaimed asphaltpavement material, reclaimed roofing shingles, and combinations thereof.11. The composition of claim 1, further characterized by an applicationtemperature of about 50° C. to 120° C. to the surface to be paved.
 12. Apaved road, including a layer of a bituminous composition, wherein thebituminous composition comprises: (a) solvent-free, oil-in-water bitumenemulsion in an amount from about 2% to about 10% by total weight of thebituminous composition, wherein the oil-in-water bitumen emulsioncomprises: (i) bitumen in an amount from about 50% to about 75% by totalweight of the bitumen emulsion, (ii) at least one active emulsifier inan amount from about 0.05% to about 2.0% by total weight of the bitumenemulsion, and (iii) water in an amount to complete the emulsion; and (b)aggregate in an amount from about 90% to about 98% by total weight ofthe bituminous composition; and wherein the bituminous composition is inan absence of bitumen having a penetration number of more than 220 dmmas determined according to an ASTM standard method D5 at 25° C., whereinthe bituminous composition is applied to the road at a temperature rangeof about 50° C. and 140° C., and wherein the bituminous composition hasa temperature range of about 50° C. to 140° C.
 13. The composition ofclaim 12, wherein the bitumen emulsion comprises the bitumen in anamount range from about 60.0% to about 70.0% by total weight of theemulsion.
 14. The composition of claim 12, wherein the bitumen emulsioncomprises the emulsifier in an amount range from about 0.08% to about0.75% by total weight of the emulsion.
 15. The composition of claim 12,wherein the bitumen emulsion comprises a member selected from the groupconsisting of naturally occurring bitumens, bitumen from crude oil,bitumen from petroleum pitch, bitumen from coal tar, sulfur-modifiedbitumen, acid-modified bitumen, and combinations thereof.
 16. Thecomposition of claim 12, wherein the bitumen emulsion comprises abitumen modified with at least one member selected from the groupconsisting of natural rubbers, synthetic rubbers, plastomers,thermoplastic resins, thermosetting resins, elastomers,styrene-butadiene-styrene, styrene-butadiene-rubber, polyisoprene,polybutylenes, butadiene-styrene rubbers, vinyl polymers, ethylene vinylacetate, and combinations thereof.
 17. The composition of claim 12,wherein the bitumen emulsion further comprises a member selected fromthe group consisting of styrene-butadiene rubber latex, polyisoprenelatex, neoprene, associative thickeners, starch, salt, and combinationsthereof.
 18. The composition of claim 12, wherein the emulsifiercomprises a member selected from the group consisting of amphotericemulsifiers, cationic emulsifiers, nonionic emulsifiers and combinationsthereof.
 19. The paved road of claim 18, wherein the amphotericemulsifier comprises a member selected from the group consisting ofsodium C-12 to C-24 alkyl amidopropyl halide methyl carboxylatebetaines, potassium C-12 to C-24 alkyl amidopropyl halide methylcarboxylate betaines, lithium C-12 to C-24 alkyl amidopropyl halidephosphate betaines, sodium C-12 to C-24 alkyl amidopropyl halidephosphate betaines, potassium C-12 to C-24 alkyl amidopropyl halidephosphate betaines, lithium C-12 to C-24 alkyl amidopropyl halidesulphate betaines, sodium C-12 to C-24 alkyl amidopropyl halide sulphatebetaines, and potassium C-12 to C-24 alkyl amidopropyl halide sulphatebetaines, lithium C-12 to C-24 alkyl amidopropyl halide methylcarboxylate betaines, C-12 to C-24 fatty imidoamines, rosin imidoamines,and combinations thereof.
 20. The paved road of claim 18, wherein thecationic emulsifier comprises a member selected from the groupconsisting of C-12 to C-24 fatty imidazolines; C-12 to C-24 fattyimidoamines; rosin imidoamines; C-12 to C-24 fatty amidoamines; rosinamidoamines; C-12 to C-24 alkyl monoamines; C-12 to C-24 alkylpolypropylene polyamines; C-12 to C-24 alkyl monoamine polyoxyethylene;C-12 to C-24 alkyl monoamine polyoxypropylene; C-12 to C-24 alkylpolypropylene monoamines polyoxyethylene; C-12 to C-24 alkylpolypropylene monoamines polyoxypropylene; C-12 to C-24 alkyl arylmonoamines; C-12 to C-24 alkyl aryl polypropylene polyamines; C-12 toC-24 quaternary amines; C-12 to C-24 alkyl ether amines; C-12 to C-24alkylether polyamines; C-12 to C-24 alkyl polypropylene polyamineN-oxides; amine derivatives of tannins; amine derivatives of phenolicresins; amine derivatives of lignins; amine-modified polyacrylates; andcombinations thereof.
 21. The composition of claim 12, wherein theaggregate comprises a member selected from the group consisting ofdense-graded aggregate, gap-graded aggregate, open-graded, stone-matrixaggregate, reclaimed asphalt pavement material, reclaimed roofingshingles, and combinations thereof.
 22. The paved road of claim 12,wherein the bituminous composition is applied to the road at atemperature range of about 50° C. to 120° C.